CHARGE-FLUCTUATION-MEDIATED SUPERCONDUCTIVITY IN THE D-P-MODEL - STRONG-COUPLING CALCULATION

Charge-fluctuation-mediated superconductivity in the simplest d-p mode l is investigated with the help of the auxiliary particle method toget her with the 1/N expansion theory. Transition temperatures, T-c, for v arious pairing symmetries are calculated by solving the linearized Eli ashberg equation retaining full momentum and frequency dependences of the vertex functions, which are repulsive almost over the entire momen tum and frequency space. Strong frequency dependences of the vertex fu nctions due to the charge fluctuation turn out to be essential to real ize such superconducting states. The extended s symmetric pairing comp osed of mainly on-site and nearest-neighbor pairing has the highest T- c similar or equal to 85 K at half-filling with a rather small charge- transfer energy where the system is metallic in contrast to the actual high-T-c materials.